Plant‐soil feedback (PSF) theory provides a powerful framework for understanding plant dynamics by integrating growth assays into predictions of whether soil communities stabilise plant–plant ...interactions. However, we lack a comprehensive view of the likelihood of feedback‐driven coexistence, partly because of a failure to analyse pairwise PSF, the metric directly linked to plant species coexistence. Here, we determine the relative importance of plant evolutionary history, traits, and environmental factors for coexistence through PSF using a meta‐analysis of 1038 pairwise PSF measures. Consistent with eco‐evolutionary predictions, feedback is more likely to mediate coexistence for pairs of plant species (1) associating with similar guilds of mycorrhizal fungi, (2) of increasing phylogenetic distance, and (3) interacting with native microbes. We also found evidence for a primary role of pathogens in feedback‐mediated coexistence. By combining results over several independent studies, our results confirm that PSF may play a key role in plant species coexistence, species invasion, and the phylogenetic diversification of plant communities.
Physical and chemical stabilisation mechanisms are now known to play a critical role in controlling carbon (C) storage in mineral soils, leading to suggestions that climate warming-induced C losses ...may be lower than previously predicted. By analysing > 9,000 soil profiles, here we show that, overall, C storage declines strongly with mean annual temperature. However, the reduction in C storage with temperature was more than three times greater in coarse-textured soils, with limited capacities for stabilising organic matter, than in fine-textured soils with greater stabilisation capacities. This pattern was observed independently in cool and warm regions, and after accounting for potentially confounding factors (plant productivity, precipitation, aridity, cation exchange capacity, and pH). The results could not, however, be represented by an established Earth system model (ESM). We conclude that warming will promote substantial soil C losses, but ESMs may not be predicting these losses accurately or which stocks are most vulnerable.
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•Delaying sample measurement is possible in many kinds of soil nitrogen conditions.•Fresh soil analysis is necessary when high nitrogen and/or organic matter content.•Air drying soil ...samples allow delaying sample measuring with low infrastructures.•Freezing soil samples allow delaying sample measuring but requires energy investment.
Scientific literature for mineral soil nitrogen content (ammonium and nitrate) measurements usually differs regarding the chosen soil sample conservation method (fresh, frozen or air-dry) before soil extraction and analysis. In addition, most of the commonly used methodologies focus on the definition of the analysis processes, regardless of the previous sample conservation methodology. With the aim to fill this gap, we performed an analysis of the conservation method effect on the nitrate, and ammonium content in frozen or air-dried samples, comparing the results with direct fresh extraction. Moreover, the effects of additional soil parameters, such as soil texture, organic matter content or mineral nitrogen content range were also studied. The results showed that both, frozen and air drying soil samples, were capable of reliably preserving the N content of soil samples in most cases. However, some ammonium losses may occur in frozen samples when a high N content (>30 mg kg−1) is present. It was also observed that air-dried soil samples can reduce the soil nitrate and increase ammonium content in samples with a high N content. It was also observed that significant amounts of organic matter in soil can alter the mineral N measured depending on the conservation method chosen. On the other hand, the soil texture presented small effects on the mineral N measurements. In any case, a broader range of soils conditions (including i.e. pH or different natural organic matter content) should be further tested to confirm our findings.
Body size is a key life-history trait that influences community assembly by affecting how ecological processes operate at the organism level. However, the extent to which the relative influences of ...ecological processes mediate the assembly of differentially sized soil organisms is still unknown. Here, we investigate the community assembly of differentially sized soil microorganisms and microfauna using a continental-scale sampling effort combined with a global-scale meta-analysis. Our results reveal a general relationship between organism body size and the stochastic-deterministic balance operating on community assembly. The smallest microorganisms (bacteria) are relatively more influenced by dispersal-based stochastic processes, while larger ones (fungi, protists and nematodes) are more structured by selection-based deterministic processes. This study elucidates a significant and consistent relationship between an organism life-history trait and how distinct ecological processes operate in mediating their respective community assemblages, thus providing a better understanding of the mechanisms supporting soil biodiversity.
Spaceborne digital elevation models (DEMs) are a fundamental input for many geoscience studies, but they still include nonnegligible height errors. Here we introduce a high‐accuracy global DEM at 3″ ...resolution (~90 m at the equator) by eliminating major error components from existing DEMs. We separated absolute bias, stripe noise, speckle noise, and tree height bias using multiple satellite data sets and filtering techniques. After the error removal, land areas mapped with ±2 m or better vertical accuracy were increased from 39% to 58%. Significant improvements were found in flat regions where height errors larger than topography variability, and landscapes such as river networks and hill‐valley structures, became clearly represented. We found the topography slope of previous DEMs was largely distorted in most of world major floodplains (e.g., Ganges, Nile, Niger, and Mekong) and swamp forests (e.g., Amazon, Congo, and Vasyugan). The newly developed DEM will enhance many geoscience applications which are terrain dependent.
Key Points
A high‐accuracy global digital elevation model (DEM) was developed by removing multiple height error components from existing DEMs
Landscape representation was improved, especially in flat regions where height error magnitude was larger than actual topography variation
The improved‐terrain DEM is helpful for any geoscience applications which are terrain dependent, such as flood inundation modelling
Plain Language Summary
Terrain elevation maps are fundamental input data for many geoscience studies. While very precise Digital Elevation Models (DEMs) based on airborne measurements are available in developed regions of the world, most areas of the globe rely on spaceborne DEMs which still include non‐negligible height errors for geoscience applications. Here we developed a new high accuracy map of global terrain elevations at 3" resolution (~90m at the equator) by eliminating multiple error components from existing spaceborne DEMs. The height errors included in the original DEMs were separated from actual topography signals and removed using a combination of multiple satellite datasets and filtering techniques. After error removal, global land areas mapped with ±2m or better accuracy increased from 39% to 58%. Significant improvements were found, especially in flat regions such as river floodplains. Here detected height errors were larger than actual topography variability, and following error removal landscapes features such as river networks and hill‐valley structures at last became clearly represented. The developed high accuracy topography map will expand the possibility of geoscience applications that require high accuracy elevation data such as terrain landscape analysis, flood inundation modelling, soil erosion analysis, and wetland carbon cycle studies.
•Laboratory ring-tests showed large coefficients of variation in soil analyses.•Estimates of soil N, P and K supply for a single field varied strongly.•Field-specific recommendations based on a ...single soil sample were inaccurate.•Fertilizer with balanced N:P:K content strongly reduced errors in recommendations.
Fertilizer recommendations are key for farmers: the investment is relatively large for smallholders and risky with unknown yield responses and variable fertilizer prices. Are agronomists able to provide useful site-specific fertilizer recommendations that reduce these uncertainties? We evaluated the influence of errors introduced due to soil sampling and chemical analysis procedures both within- and among laboratories on fertilizer recommendations. Using what we consider to be conservative estimates of the uncertainty in estimating soil supply of N, P and K in a single composite soil sample, the resulting 90% confidence interval of fertilizer recommendations ranged from 86 to 186, 0–58 and 38–114 kg N, P and K ha−1 respectively. The numerous laboratory services and digital applications providing field-specific recommendations appear to promise more accuracy than soil analysis can realistically deliver. We conclude that a field-specific fertilizer recommendation based on a single composite soil sample is indeed a pipe-dream.
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